1. Field of the Invention
The present invention generally relates to the removable attachment of Partial denture which can be fabricated as a sliding and locking attachment and in particular relates to the removable attachment including at least one protruder both having a function as a rigid latch when the wearer masticates any foods and another function as a spring loaded rod when the user pushes out the slider by his fingertip for clearing the attachment used. 2. Description of the Prior Art
In the prior art, there are a variety of removable attachments for partial dentures. For example, Chayes type attachment (developed in U.S.A.), Ceka-anchor attachment (developed in Belgium) and Inoue type attachment (developed in Japan). Such three attachments have common characteristics in their construction but also have common defects.
Nevertheless they are troublesome to remove, after every mealtime. For cleaning by water, they must frequently be removed from the oral inside to the oral outside. Further, they are easily damaged by the mechanical shock inflicted on the abutment teeth they are connected to. In light of the physiology, when the repeated mechanical shock, generated when removing those attachments, are directly and greatly inflicted upon hte abutment natural tooth, it affects the abutment tooth of the user as a fatal blow. In other words, the repeated mechanical shocks will cause the root of the abutment natural tooth to be shortened and then cause the periodontal tissue of the abutment tooth to be loaded excessively. Hence, the excessively loaded shock to the abutment teeth can cause the periodontal tissue to become inflamed. They can only be operated on with special instruments which are normally expensive.
In spite of using the special instruments, according to the condition of the natural teeth of the patient, it is often impossible to administer medicine to the patient, and even if the patient displays a normal condition of natural teeth, it is very difficult to administer medicine to the patient, because the surgical procedure requires a high degree of precision. Although, they practice with high precision on the patient, a sudden separation of a loosened partial denture can occur when even small amounts of wear or loosening of the attachment has occurred.
Further, the prior art attachments have a common and prime shortcoming apparent upon its removal in a vertical direction about the row of teeth or occlusal surface of teeth. That is, if the wearer masticates foods with adhesive characteristics, such as gum, caramel, hard candy, taffy, jelly beans, marshmellow and etc., those attachments can be easily removed, even if, the user or wearer never intended to remove the attachment. This is due to said removal in the vertical direction because the movement of the vertical force is usually generated during masticating foods having adhesive feature.
For all that, if any device is provided within those attachments for preventing the vertical movement, mechanical shock can be directly inflicted on the abutment natural tooth due to the construction feature thereof, and which causes the root of the abutment tooth to be shortened and the periodontal tissue to become inflamed.
One of the prior arts is provided within U.S. Pat. No. 4,302,187 issued on Nov. 24, 1981 which is my invention and is a parent invention relative to this application. There is described a removable attachment for a partial denture without the mentioned blemishes hereinbefore. The attachment, as described in the above U.S. Pat. No. 4,302,187, is characterized in that the direction of the movement of the slider member is horizontal instead of vertical as in the prior art, and a protruder attached to a crowned abutment natural tooth has a minimum length for avoiding the mechanical shock generated when removing itself, and which is provided for connecting the abutment tooth to the attachment by a slider and in that, the attachment can be manufactured and hence minimize the cost. Further the attachment can be installed without the need for specialized instruments but with high mechanical precision. However, in light of the general phenomenon of mastication that is, vertical force primarily generated during mastication and also secondly, the lateral movement generated during mastication, there is a disadvantage that if the wearer masticates foods with strong adhesive features or characteristics of relatively low softness and relatively high hardness, the slider member of the above mentioned attachment can be, sometimes, slid in the lateral direction. Also, there is provided the protruder having a minimum length for preventing the mechanical shock generated when removing the attachment. However, I have found that there is another phenomenon, that is, another shock should be generated when masticating foods. The later shock is generated due to the difference between length of possible movement of tooth and gingiva. According to a theory in the dental field, it is acceptable to rock the tooth by 0.08 mm-0.21 mm as a positive reaction and the gingiva by 0.27 mm-0.38 mm as a positive reaction. As suggested in the above range of data, the movement of teeth and gingiva are needed for maintaining the given lifes thereof. However, the excessive movements thereof over that of the above mentioned ranges of movement are represented to reduce or destroy the given lifes of the tissue and the root of the tooth as the negative reaction. However, the attachment of Patent 4,302,187 is without a device for preventing these kind of shocks.
Also, in the above mentioned patent 4,302,187, when the average height of teeth is lowered, the retaining force of the attachment in the locked (stable) position is weakened due to the constructive shape thereof. For avoiding this defect, the model of the attachment should be distinguished by two types, that is, one type is applied to wearer when the average height of teeth is either normal or high and the other type is when the average thereof is low. Further, in the case of the older permanent teeth, that is, of the physiologically very worn teeth, there is a disadvantage that the attachment of Patent 4,302,187 can not be applied to wearer. For effectively meeting the phenomenon of the occlusal surface, the occlusal surface of maxillary teeth must be matched with that of the corresponding mandible teeth. However, even if the occlusal surfaces are matched substantially to each other, when the teeth are very worn and in particular, the used attachment of maxillary teeth is matched unfortunately with the attachment of the corresponding mandible tooth, the attachment can be slid in the lateral direction by the combined force in the downwardly inclined and lateral direction generated when masticating foods. Once the above-mentioned sliding of the attachment occurs from the stable or locking position thereof, the wearer cannot masticate any more.
When the missing tooth is, for example, a tooth between the bicuspid and molar, the technique of the fixed bridge is generally applied thereto. The bridge is generally distinguished by two kinds thereof, that is, one is a fixed bridge and the other one is a removable bridge, but the latter one is closer to the classification of the partial denture. Also, in the fixed bridge field, it is generally known that a pontic corresponding to the missing tooth is connected between the abutment natural teeth so as to minimize the contacting portion of pontic to the surface of gingiva. The minimal contacted portion of pontic with the surface of the gingiva causes an embrasure to be greatly created between the pontic and the gingiva as well as the abutment natural teeth. The great embrasure is an extra shape which does not appear in the natural oral. Hence, the wearer having the great embrasure in his oral is indisposed or inconvenienced with the embrasure. But in light of oral physiology, the great embrasure does not have bad effects on oral health because there is provided a massage effect of gingiva by passing a piece of the foods through the embrasure. However, in accordance with the old habit of no embrasure or small embrasure of wearer, he requests often that the dentist blocks his embrasure so that food may not pass through. If the embrasure is to be blocked, the portion of the pontic contacting to the gingiva must be broadened. However, the broadened contacting portion thereof causes easily the portion of gingiva under the broadened portion to be inflamed, so that, for treating the inflamed portion the fixed bridge must be removed from the fixed position, where the inflammation resulted from the storage of a secretion of the tissue and a leftover foods under the broadened portion of the pontic. Also, in light of the mechanism of the fixed bridge, as the pontic connected between the abutment teeth is maintained in the lifting position from the gingiva, when masticating the foods, the masticating force is applied to the occlusal surface of the pontic like to the occlusal surface of the natural tooth. The force applied to the pontic is distributed to both abutment teeth while the pontic is never supported by gingiva. Thus, thnt of teeth and gingiva are needed for maintaining the given lifes thereof. However, the excessive movements thereof over that of the above mentioned ranges of movement are represented to reduce or destroy the given lifes of the tissue and the root of the tooth as the negative reaction. However, the attachment of Patent 4,302,187 is without a device for preventing these kind of shocks.
Also, in the above mentioned patent 4,302,187, when the average height of teeth is lowered, the retaining force of the attachment in the locked (stable) position is weakened due to the constructive shape thereof. For avoiding this defect, the model of the attachment should be distinguished by two types, that is, one type is applied to wearer when the average height of teeth is either normal or high and the other type is when the average thereof is low. Further, in the case of the older permanent teeth, that is, of the physiologically very worn teeth, there is a disadvantage that the attachment of Patent 4,302,187 can not be applied to wearer. For effectively meeting the phenomenon of the occlusal surface, the occlusal surface of maxillary teeth must be matched with that of the corresponding mandible teeth. However, even if the occlusal surfaces are matched substantially to each other, when the teeth are very worn and in particular, the used attachment of maxillary teeth is matched unfortunately with the attachment of the corresponding mandible tooth, the attachment can be slid in the lateral direction by the combined force in the downwardly inclined and lateral direction generated when masticating foods. Once the above-mentioned sliding of the attachment occurs from the stable or locking position thereof, the wearer cannot masticate any more.
When the missing tooth is, for example, a tooth between the bicuspid and molar, the technique of the fixed bridge is generally applied thereto. The bridge is generally distinguished by two kinds thereof, that is, one is a fixed bridge and the other one is a removable bridge, but the latter one is closer to the classification of the partial denture. Also, in the fixed bridge field, it is generally known that a pontic corresponding to the missing tooth is connected between the abutment natural teeth so as to minimize the contacting portion of pontic to the surface of gingiva. The minimal contacted portion of pontic with the surface of the gingiva causes an embrasure to be greatly created between the pontic and the gingiva as well as the abutment natural teeth. The great embrasure is an extra shape which does not appear in the natural oral. Hence, the wearer having the great embrasure in his oral is indisposed or inconvenienced with the embrasure. But in light of oral physiology, the great embrasure does not have bad effects on oral health because there is provided a massage effect of gingiva by passing a piece of the foods through the embrasure. However, in accordance with the old habit of no embrasure or small embrasure of wearer, he requests often that the dentist blocks his embrasure so that food may not pass through. If the embrasure is to be blocked, the portion of the pontic contacting to the gingiva must be broadened. However, the broadened contacting portion thereof causes easily the portion of gingiva under the broadened portion to be inflamed, so that, for treating the inflamed portion the fixed bridge must be removed from the fixed position, where the inflammation resulted from the storage of a secretion of the tissue and a leftover foods under the broadened portion of the pontic. Also, in light of the mechanism of the fixed bridge, as the pontic connected between the abutment teeth is maintained in the lifting position from the gingiva, when masticating the foods, the masticating force is applied to the occlusal surface of the pontic like to the occlusal surface of the natural tooth. The force applied to the pontic is distributed to both abutment teeth while the pontic is never supported by gingiva. Thus, the pressure owning to the masticating force is transfered to the both abutment tooth from the center point of the occlusal surface of the pontic, in the inclined direction from the central point. Of course, during this time, the excessively loaded shock is applied to the abutment natural teeth.
For this case, Plotnick's attachment (U.S. Pat. No. 2,835,034) of the prior arts can be considered usable, but in the Plotnick's attachment, the pressure owing to the mastication is, also, applied to the rest of the attachment and hence applied to both abutment teeth in the same way with the above fixed bridge case. Lastly, the Plotnick's attachment cannot be used to replace the fixed bridge therewith so as to prevent the defects from the fixed bridge. Further, the removal direction from the locked position of the Plotnick's attachment is vertical, so that the attachment can be removed suddenly when masticating foods having adhesive features.
It is therefore an object of the present invention to provide a removable attachment for a partial denture which can be used in a variety of applications including cases where the deformation of the remaining natural teeth is provided for anyway and where the abutment teeth are few in number or somewhat damaged.
It is a further object of the present invention to provide a removable attachment for a partial denture which can be used for avoiding the above mentioned shortcomings from the fixed bridge.
It is another object of the instant invention to provide a removable attachment for a partial denture, which can overcome the defects from the prior arts such as U.S. Pat. 4,302,187.
It is yet another object to the present invention to provide a removable attachment for a partial denture, which can be safely used and which include an individual movable member having at least one protruder with both the function as a rigid latch when the wearer mastificates foods and a function as a spring loaded rod when the wearer pushes out the slider with his fingertip in the lateral direction.
It is a further object of the present invention to provide a removal attachment for a partial denture, which can be sticked substantially, against the lateral movement of when strongly masticating foods, the slider fast to the body.
It is an object of the present invention to provide a removable attachment for an partial denture where the shock in the vertical direction, generated when masticating foods and by the difference span between length of possible movement of tooth and gingiva when an artificial tooth was used for the missing tooth, is not directly applied to the roots and the periodontal tissue of the abutment natural tooth.
It is still another object of the present invention to provide a removable attachment for a partial denture which is a unity type and which can be used with the impertinence relation to the anatomical condition of the teeth of the patient.
In accordance with the aspects of the present invention, there is provided the individual movable member which is mounted into the slider, which has at least one protruder extended through at least one hole formed with the bottom portion of slider to the outside thereof for reflecting the view point which in the general attachment for a partial denture, the stability and retaining force of the attachment are of prime importance, where the individual movable member can be moved individually with the slider and also has a upper surface therof, almost covering the upper surface of the slider as an occlusal surface of natural tooth.